Pulse oximetry device and method of operating a pulse oximetry device

ABSTRACT

A pulse oximetry device includes a light emission device configured to emit light with a wavelength in a first wavelength interval and light with a wavelength in a second wavelength interval, a first light detector configured to detect light with a wavelength in the first wavelength interval, but not to respond to light with a wavelength in the second wavelength interval, and a second light detector configured to detect light with a wavelength in the first wavelength interval and detect light with a wavelength in the second wavelength interval, wherein the first light detector has a first light reception surface, the second light detector has a second light reception surface, and the first light reception surface and the second light reception surface are arranged in a common plane and are interleaved with one another.

TECHNICAL FIELD

This disclosure relates to a pulse oximetry device and a method ofoperating a pulse oximetry device.

BACKGROUND

Pulse oximetry devices for non-invasive determination of an arterialoxygen saturation in the blood of a human patient are known. In suchpulse oximetry devices, determination of the arterial oxygen saturationis carried out by a light absorption measurement while shining lightthrough the skin of the patient.

SUMMARY

We provide a pulse oximetry device including a light emission deviceconfigured to emit light with a wavelength in a first wavelengthinterval and light with a wavelength in a second wavelength interval, afirst light detector configured to detect light with a wavelength in thefirst wavelength interval, but not to respond to light with a wavelengthin the second wavelength interval, and a second light detectorconfigured to detect light with a wavelength in the first wavelengthinterval and detect light with a wavelength in the second wavelengthinterval, wherein the first light detector has a first light receptionsurface, the second light detector has a second light reception surface,and the first light reception surface and the second light receptionsurface are arranged in a common plane and are interleaved with oneanother.

We also provide a method of operating a pulse oximetry device includingemitting light with a wavelength in a first wavelength interval andsimultaneously emitting light with a wavelength in a second wavelengthinterval; recording a first measurement signal with a first lightdetector configured to detect light with a wavelength in the firstwavelength interval, but not to respond to light with a wavelength inthe second wavelength interval; recording a second measurement signalwith a second light detector configured to detect light with awavelength in the first wavelength interval and detect light with awavelength in the second wavelength interval, wherein the first lightdetector has a first light reception surface, the second light detectorhas a second light reception surface, and the first light receptionsurface and the second light reception surface are arranged in a commonplane and are interleaved with one another; and calculating an oxygensaturation from the first measurement signal and the second measurementsignal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a pulse oximetry device having a lightemission device and a light detection device.

FIG. 2 schematically shows a light emission device according to analternative example.

FIG. 3 schematically shows a plan view of the light detection deviceaccording to one example.

FIG. 4 schematically shows a sectional side view of a housing of thepulse oximetry device according to a first example.

FIG. 5 schematically shows a sectional side view of the housing of thepulse oximetry device according to a second example.

FIG. 6 schematically shows a sectional side view of the housing of thepulse oximetry device according to a third example.

LIST OF REFERENCES

-   100 pulse oximetry device-   200 light emission device-   210 first light-emitting diode structure-   211 light with a wavelength in a first wavelength interval-   220 second light-emitting diode structure-   221 light with a wavelength in a second wavelength interval-   230 light-emitting diode chip-   231 first light-emitting diode chip-   232 second light-emitting diode chip-   300 light detection device-   310 first light detector-   311 first light reception surface-   312 filter-   320 second light detector-   321 second light reception surface-   400 housing-   401 upper side-   410 emitter cavity-   411 wall-   420 further emitter cavity-   430 detector cavity-   440 diaphragm structure-   450 cover structure-   500 body part

DETAILED DESCRIPTION

Our pulse oximetry device comprises a light emission device configuredto emit light with a wavelength in a first wavelength interval and lightwith a wavelength in a second wavelength interval, a first lightdetector configured to detect light with a wavelength in the firstwavelength interval, but not to respond to light with a wavelength inthe second wavelength interval, and a second light detector configuredto detect light with a wavelength in the first wavelength interval anddetect light with a wavelength in the second wavelength interval.

The pulse oximetry device has only a small number of components and can,therefore, be configured compactly and produced economically. Since thepulse oximetry device has two light detectors, which make it possible todiscriminate between light with a wavelength in the first wavelengthinterval and light with a wavelength in the second wavelength interval,the light emission device of this pulse oximetry device cansimultaneously emit light with a wavelength in the first wavelengthinterval and light with a wavelength in the second wavelength interval.Operation of the pulse oximetry device is therefore advantageouslyparticularly straightforwardly possible.

The first wavelength interval and the second wavelength interval neednot overlap one another. Advantageously, the light with a wavelength inthe wavelength interval and the light with a wavelength in the secondinterval may thereby differ significantly so that clear discriminationbetween oxygenated hemoglobin and deoxygenated hemoglobin is madepossible.

The first wavelength interval or the second wavelength interval may liebelow 810 nm, and may in particular comprise a wavelength of 660 nm. Theother wavelength interval in this case lies above 810 nm, and may inparticular comprise a wavelength of 940 nm. Light with wavelengths inthese wavelength intervals has proven particularly suitable for use inpulse oximetry devices.

The first light detector may have a filter configured to filter outlight with a wavelength in the second wavelength interval. It is therebypossible to ensure that the first light detector does not respond tolight with a wavelength in the second wavelength interval. In this way,comparison of measurement signals delivered by the first light detectorand the second light detector makes it possible to discriminate betweenthe signal components caused by light with a wavelength in the firstwavelength interval and by light with a wavelength in the secondwavelength interval.

The first light detector may have a first light reception surface. Inthis case, the second light detector has a second light receptionsurface. The first light reception surface and the second lightreception surface are arranged in a common plane and interleaved withone another. Advantageously, homogeneous illumination of the first lightreception surface of the first light detector and the second lightreception surface of the second light detector can thereby be ensured.This advantageously avoids a measurement signal determined by the pulseoximetry device being vitiated, for example, by geometrical shadowing.

The light emission device may be configured to emit light with awavelength in the second wavelength interval with a higher power thanlight with a wavelength in the first wavelength interval, in particularwith a power at least four times as high, in particular with a power atleast eight times as high. For example, the light emission device may beconfigured to emit light with a wavelength in the second wavelengthinterval with a power nine times as high as light with a wavelength inthe first wavelength interval. The achievable effect is that ameasurement signal determined by the second light detector of the pulseoximetry device is dominated by the detection of light with a wavelengthin the second wavelength interval, while the detection of light with awavelength in the first wavelength interval is negligible. In this way,the first light detector and the second light detector of the pulseoximetry device advantageously allow almost separate detection of lightwith a wavelength in the first wavelength interval and light with awavelength in the second wavelength interval.

The light emission device may have a first light-emitting diodestructure configured to emit light with a wavelength in the firstwavelength interval, and a second light-emitting diode structureconfigured to emit light with a wavelength in the second wavelengthinterval. Since, in the pulse oximetry device, it is not necessary toemit light with a wavelength in the first wavelength interval and lightwith a wavelength in the second wavelength interval separately from oneanother, the first light-emitting diode structure and the secondlight-emitting diode structure of the light emission device may beinterleaved such that the first light-emitting diode structure and thesecond light-emitting diode structure are always operated together sothat the light emission device can advantageously be configuredparticularly simply.

The first light-emitting diode structure and the second light-emittingdiode structure may be arranged in a common light-emitting diode chip.Advantageously, the light emission device is therefore configuredparticularly compactly.

The first light-emitting diode structure and the second light-emittingdiode structure may be arranged/stacked on top of one another. In thiscase, the first light-emitting diode structure and the secondlight-emitting diode structure may, for example, be configured as layersof the common light-emitting diode chip arranged on top of one another.The first light-emitting diode structure and the second light-emittingdiode structure may in this case electrically connect in series.Advantageously, the light emission device has particularly compactexternal dimensions and can be obtained economically. By electricalinterconnection of the first light-emitting diode structure and thesecond light-emitting diode structure of the light emission device inseries, it is advantageously possible to ensure that electrical currentswith the same current strength always flow through the firstlight-emitting diode structure and the second light-emitting diodestructure.

The light emission device may have a first light-emitting diode chiphaving the first light-emitting diode structure, and a secondlight-emitting diode chip having the second light-emitting diodestructure. Advantageously, the light-emitting diode chips of the lightemission device can therefore be formed by economically availablestandard components.

The pulse oximetry device may have a housing with an emitter cavity anda detector cavity. In this case, the light emission device is arrangedin the emitter cavity, while the first light detector is arranged in thedetector cavity. Advantageously, the housing of the pulse oximetrydevice may in this case be configured extremely compactly. By virtue ofthe arrangement of the light emission device and the first lightdetector in separate cavities, undesired direct crosstalk between thelight emission device and the first light detector, which impairs themeasurement quality, is advantageously avoided.

The second light detector may likewise be arranged in the detectorcavity. Advantageously, it is thereby possible to ensure that the firstlight detector and the second light detector are arranged close to oneanother so that vitiation by geometrical effects of a measurement signaldetermined by the pulse oximetry device can be avoided.

The emitter cavity and the detector cavity may be open to a commonsurface of the housing. During operation of the pulse oximetry device,this common surface of the housing of the pulse oximetry device may facetoward a human patient's body part to be examined.

A wall of the emitter cavity may form an optical reflector.Advantageously, the optical reflector formed by the wall of the emittercavity may cause concentration of the light emitted by the lightemission device so that a higher radiation intensity of the lightemitted by the light emission device can also be obtained. This, forexample, may make it possible for the light emitted by the lightemission device of the pulse oximetry device to reach deeper skin layersof a patient to be examined so that an increased measurement accuracycan be made possible.

The housing may have a further emitter cavity in which a further lightemission device is arranged. This can make it possible to illuminatewith the pulse oximetry device a larger skin surface of a patient to beexamined, which may lead to an improved signal-to-noise ratio.

A method of operating a pulse oximetry device comprises steps ofemitting light with a wavelength in a first wavelength interval, andsimultaneously emitting light with a wavelength in a second wavelengthinterval, recording a first measurement signal with a first lightdetector configured to detect light with a wavelength in the firstwavelength interval, but not to respond to light with a wavelength inthe second wavelength interval, recording a second measurement signalwith a second light detector configured to detect light with awavelength in the first wavelength interval and detect light with awavelength in the second wavelength interval, and calculating an oxygensaturation from the first measurement signal and the second measurementsignal.

Since the light with a wavelength in the first wavelength interval andthe light with a wavelength in the second wavelength interval aresimultaneously emitted in this method, the method can advantageously becarried out particularly simply and rapidly. The method may in this caseadvantageously be used to operate a pulse oximetry device having only asmall number of components, and can therefore be economically obtained.

In this method, the recording of the first measurement signal with thefirst light detector and of the second measurement signal with thesecond light detector allows separation of the component of the lightwith a wavelength in the first wavelength interval and the component ofthe light with a wavelength in the second wavelength interval. This isachieved by the first measurement signal being recorded with the firstlight detector which responds only to light with a wavelength in thefirst wavelength interval, but not to light with a wavelength in thesecond wavelength interval.

A difference signal may be formed from the difference of the firstmeasurement signal and the second measurement signal. In this case, theoxygen saturation is calculated from the first measurement signal andthe difference signal. Advantageously, the formed difference signalessentially indicates the component of the light with a wavelength inthe second wavelength interval. Use of the first measurement signal andthe difference signal therefore allows particularly accurate calculationof the oxygen saturation.

The light with a wavelength in the second wavelength interval may beemitted with a higher power than the light with a wavelength in thefirst wavelength interval, in particular with a power that is at leastfour times as high, in particular with a power that is at least eighttimes as high. For example, the light with a wavelength in the secondwavelength interval may be emitted with a power that is nine times ashigh as the light with a wavelength in the first wavelength interval.Advantageously, the effect thereby achieved is that the secondmeasurement signal, recorded with the second light detector, isdominated by the component of the light with a wavelength in the secondwavelength interval. In this way, discrimination of the components ofthe light with a wavelength in the first wavelength interval and thelight with a wavelength in the second wavelength interval is facilitatedso that the method advantageously allows particularly accuratecalculation of the oxygen saturation.

The above-described properties, features and advantages, as well as theway in which they are achieved, will become more clearly and readilycomprehensible in conjunction with the following description of theexamples, which will be explained in more detail in connection with thedrawings.

FIG. 1 shows a highly schematized representation of a pulse oximetrydevice 100. The pulse oximetry device 100 may be used for non-invasivedetermination of an oxygen saturation in the blood of a patient.Determination of the oxygen saturation is carried out by a lightabsorption measurement while illuminating the skin of a body part 500,for example, a finger of the patient.

The pulse oximetry device 100 comprises a light emission device 200 anda light detection device 300.

The light emission device 200 comprises a first light-emitting diodestructure 210 and a second light-emitting diode structure 220. The firstlight-emitting diode structure 210 is configured to emit light 211 witha wavelength in a first wavelength interval. The second light-emittingdiode structure 220 is configured to emit light 221 with a wavelength ina second wavelength interval.

The first wavelength interval and the second wavelength intervalpreferably do not overlap one another. Preferably, one of the wavelengthintervals lies below 810 nm, the other wavelength interval lies above810 nm. The wavelength interval lying below 810 nm preferably comprisesa wavelength of 660 nm. The wavelength interval lying above 810 nmpreferably comprises a wavelength of 940 nm. In the example shown inFIG. 1, the first wavelength interval lies below 810 nm and comprisesthe wavelength of 660 nm. The second wavelength interval in this examplelies above 810 nm and comprises the wavelength of 940 nm. Preferably,the first light-emitting diode structure 210 is configured in thisexample to emit light 211 with a wavelength of about 660 nm. The secondlight-emitting diode structure 220 is in this example preferablyconfigured to emit light 221 with a wavelength of about 940 nm.

In the example of pulse oximetry device 100 as represented in FIG. 1,the first light-emitting diode structure 210 and the secondlight-emitting diode structure 220 of the light emission device 200 arearranged in a common light-emitting diode chip 230. In this case, thefirst light-emitting diode structure 210 and the second light-emittingdiode structure 220 are arranged/stacked on top of one another in thelight-emitting diode chip 230. The light-emitting diode chip 230 mayalso be referred to as a stack LED or a dual-wavelength LED.

The light detection device 300 of the pulse oximetry device 100comprises a first light detector 310 and a second light detector 320.The first light detector 310 has a first light reception surface 311.The second light detector 320 has a second light reception surface 321.The first light detector 310 and the second light detector 320 of thelight detection device 300 may, for example, be configured asphotodiodes.

The first light detector 310 of the light detection device 300 of thepulse oximetry device 100 is configured to detect light 211 with awavelength in the first wavelength interval striking the first lightdetector 310, but not to respond to light 221 with a wavelength in thesecond wavelength interval striking the first light detector 310. Thefirst light detector 310 is configured to deliver a first measurementsignal, the size of which depends on the brightness of the light 211with a wavelength in the first wavelength interval striking the firstlight detector 310. Light 221 with a wavelength in the second wavelengthinterval striking the first light detector 310 preferably does notinfluence the size of the first measurement signal delivered by thefirst light detector 310, or influences it only to an extent which is assmall as possible. This is achieved in the first light detector 310 ofthe light detection device 300 by a filter 312 arranged on the firstlight reception surface 311 of the first light detector 310, this filterbeing configured to filter out light 221 with a wavelength in the secondwavelength interval 221, but to transmit light 211 with a wavelength inthe first wavelength interval.

The second light detector 320 of the light detection device 300 of thepulse oximetry device 100 is configured to detect light 211 with awavelength in the first wavelength interval striking the second lightreception surface 321 of the second light detector 320 and light 221with a wavelength in the second wavelength interval striking the secondlight reception surface 321. The second light detector 320 is configuredto generate a second measurement signal, the size of which depends onthe brightness of the light 211 with a wavelength in the firstwavelength interval striking the second light reception surface 321 andon the brightness of the light 221 with a wavelength in the secondwavelength interval striking the second light reception surface 321.

Light 211 with a wavelength in the first wavelength interval and light221 with a wavelength in the second wavelength interval, shining intothe body part 500, is absorbed with different strength depending on thearterial oxygen saturation. From a measurement of the brightness of thelight 211 with a wavelength in the first wavelength interval and light221 with a wavelength in the second wavelength interval, reflected inthe body part 500 or transmitted through the body part 500, it istherefore possible to determine the arterial oxygen saturation.

To this end, it is necessary to determine the brightness of thereflected or transmitted light 211 with a wavelength in the firstwavelength interval and the brightness of the reflected or transmittedlight 221 with a wavelength in the second wavelength interval at leastapproximately separately. By the light emission device 200 of the pulseoximetry device 100, light 211 with a wavelength in the first wavelengthinterval and light 221 with a wavelength in the second wavelengthinterval is simultaneously emitted. It is therefore necessary to recordthe brightness of the reflected or transmitted light 211 with awavelength in the first wavelength interval and the brightness of thereflected or transmitted light 221 with a wavelength in the secondwavelength interval at least approximately separately with the aid ofthe light detection device 300.

One possibility consists in configuring the light emission device 200such that light 221 with a wavelength in the second wavelength intervalis emitted with a higher power than light 211 with a wavelength in thefirst wavelength interval. In this case, the light 221 is preferablyemitted with a power that is at least four times as high, in particularwith a power that is at least eight times as high, as the light 211 witha wavelength in the first wavelength interval. For example, the light221 with a wavelength in the second wavelength interval may be emittedwith a power that is nine times as high as the light 211 with awavelength in the first wavelength interval.

In this case, the second measurement signal recorded by the second lightdetector 320 of the light detection device 300 is dominated by thebrightness of the light 221 with a wavelength in the second wavelengthinterval striking the second light reception surface 321 of the secondlight detector 320, while the influence of the light 221 with awavelength in the first wavelength interval striking the second lightreception surface 321 of the second light detector 320 is negligiblysmall. This makes it possible to assume as an approximation that thesecond measurement signal recorded by the second light detector 320 ofthe light detection device 300 depends only on the brightness of thereflected or transmitted light 221 with a wavelength in the secondwavelength interval.

The first measurement signal recorded by the first light detector 310 ofthe light detection device 300 indicates the brightness of the reflectedor transmitted light 211 with a wavelength in the first wavelengthinterval. This makes it possible to calculate the arterial oxygensaturation in the body part 500 from the measurement signal delivered bythe first light detector 310 and the measurement signal delivered by thesecond light detector 320, the systematic error entailed being small.

An alternative possibility consists of subtracting the first measurementsignal recorded by the first light detector 310 of the light detectiondevice 300 from the second measurement signal recorded by the secondlight detector 320 of the light detection device 300. The formeddifference signal depends approximately only on the brightness of thereflected or transmitted light 221 with a wavelength in the secondwavelength interval striking the second light reception surface 321 ofthe second light detector 320. In this case, it is unimportant whetherthe light 211 with a wavelength in the first wavelength interval and thelight 221 with a wavelength in the second wavelength interval areemitted with the same power or different powers by the light emissiondevice 200 of the pulse oximetry device 100. The first measurementsignal recorded by the first light detector 310 of the light detectiondevice 300 depends on the brightness of the reflected or transmittedlight 211 with a wavelength in the first wavelength interval strikingthe first light reception surface 311 of the first light detector 310.This makes it possible to calculate the arterial oxygen saturation inthe body part 500 from the first measurement signal delivered by thefirst light detector 310 and the second measurement signal delivered bythe second light detector 320.

FIG. 2 shows a schematic sectional side view of the light emissiondevice 200 of the pulse oximetry device 100 according to an alternativeexample. In the example represented in FIG. 2, the light emission device200 also comprises a first light-emitting diode structure 210 that emitslight 211 with a wavelength in the first wavelength interval and asecond light-emitting diode structure 220 that emits light 221 with awavelength in the second wavelength interval. In the example of thelight emission device 200 as represented in FIG. 2, however, the firstlight-emitting diode structure 210 and the second light-emitting diodestructure 220 are not integrated into a common light-emitting diodechip. Instead, the first light-emitting diode structure 210 is arrangedin a first light-emitting diode chip 231 and the second light-emittingdiode structure 220 is arranged in a second light-emitting diode chip232. The first light-emitting diode chip 231 and the secondlight-emitting diode chip 232 together form the light emission device200. Preferably, the first light-emitting diode chip 231 and the secondlight-emitting diode chip 232 are arranged close to one another.

FIG. 3 shows in a schematized representation a plan view of the firstlight reception surface 311 of the first light detector 310 and of thesecond light reception surface 321 of the second light detector 320 ofthe light detection device 300 of the pulse oximetry device 100. Thelight reception surface 311 of the first light detector 310 and thesecond light reception surface 321 of the second light detector 320 arearranged in a common plane and are interleaved with one another. In theexample shown in FIG. 3, the first light reception surface 311 and thesecond light reception surface 321 each have a comb-shaped fingerstructure. The finger structures of the first light reception surface311 and the finger structure of the second light reception surface 321are interdigitated with one another. By the interleaved arrangement ofthe first light reception surface 311 and the second light receptionsurface 321, it is possible to ensure that the first light receptionsurface 311 and the second light reception surface 321 are essentiallyilluminated equally by the light 211, 221 reflected or transmitted inthe body part 500, without geometrical effects, for example, shadowing,leading to different brightnesses recorded by the first light detector310 and by the second light detector 320. It is, however, also possibleto configure the light reception surfaces 311, 321 of the lightdetectors 310, 320 of the light detection device 300 other than asrepresented in FIG. 3.

FIG. 4 shows a schematic sectional side view of an exemplary housing 400of the pulse oximetry device 100. The housing 400 may, for example, bemanufactured in chip-on-board or MID technology.

The housing 400 has an emitter cavity 410, a further emitter cavity 420and a detector cavity 430. The three cavities 410, 420, 430 are arrangednext to one another and are all open toward an upper side 401 of thehousing 400. The cavities 410, 420, 430 are therefore configured asrecesses arranged on the upper side 401 of the housing 400. The emittercavities 410, 420 of the housing 400 widen from the respective bottomregion of the cavities 410, 420 toward the upper side 401 of the housing400 in the shape of a funnel. The detector cavity 430 may also widenfrom its bottom region toward the upper side 401 of the housing 400.

The light emission device 200 of the pulse oximetry device 100 isarranged at the bottom region of the emitter cavity 410 of the housing400. Light 211, 221 emitted by the light emission device 200 can emergefrom the emitter cavity 410 on the upper side 401 of the housing 400. Awall 411 of the emitter cavity 410 widening conically toward the upperside 401 may form an optical reflector, which may cause concentration ofthe light 211, 221 emitted by the light emission device 200.

Arranged in the further emitter cavity 420 of the housing 400, there isa further light emission device 200 configured in the same way as thelight emission device 200 arranged in the emitter cavity 410. Thefurther light emission device 200 arranged in the further emitter cavity420 may be used to illuminate a larger skin surface of the body part 500of the patient to be examined with the pulse oximetry device 100. Thefurther emitter cavity 420 and the further light emission device 200arranged in the further emitter cavity 420 may, however, also beomitted.

The first light detector 310 and the second light detector 320 of thelight detection device 300 are arranged at the bottom region of thedetector cavity 430 of the housing 400 of the pulse oximetry device 100.As an alternative, it would be possible to arrange the first lightdetector 310 and the second light detector 320 of the light detectiondevice 300 in separate cavities. It is, however, preferred to arrangeboth light detectors 310, 320 of the light detection device 300 in thecommon detector cavity 430. A wall of the detector cavity 430 wideningtoward the upper side 401 of the housing 400 may be used to collectlight incident in the detector cavity 430 and to direct it to the lightreception surfaces 311, 321 of the light detectors 310, 320 of the lightdetection device 300.

Since the light emission device 200 and the light detection device 300of the pulse oximetry device 100 are arranged in separate cavities 410,420, 430 of the housing 400 of the pulse oximetry device 100, directcrosstalk between the light emission device 200 and the light detectiondevice 300 is advantageously reduced or entirely avoided. This meansthat none, or only a little, of the light 211, 221 emitted by the lightemission device 200 reaches the light detection device 300 on a directpath, but only does so after reflection in the body part 500 to beexamined.

An optically transparent casting material, for example, a castingmaterial which comprises silicone, may be arranged in the cavities 410,420, 430 of the housing 400. In this case, the light emission device200, the further light emission device 200 and/or the light detectiondevice 300 are embedded in the casting material arranged in therespective cavity 410, 420, 430, and are thereby protected from damageby external influences. A casting material may also be arranged only inthe emitter cavities 410, 420 or only in the detector cavity 430.

FIG. 5 shows a schematic sectional side view of the housing 400 of thepulse oximetry device 100 according to an alternative example. Thevariant of the housing 400 as shown in FIG. 5 differs from the variantof the housing 400 as represented in FIG. 4 in that a diaphragmstructure 440 is arranged on the upper side 401 of the housing 400. Thediaphragm structure 440 may be configured in one piece continuously withthe part of the housing 400 comprising cavities 410, 420, 430, or it maybe arranged as a separate component on the upper side 401 of the housing400. In its regions arranged over the cavities 410, 420, 430, thediaphragm structure 440 has diaphragm openings. The diaphragm openingsmay have diameters which are less than the aperture diameters of thecavities 410, 420, 430. In this way, the diaphragm structure 440 maycause a further reduction of undesired crosstalk between the lightemission devices 200 and the light detection device 300 of the pulseoximetry device 100.

FIG. 6 shows a schematic sectional side view of another alternativeexample of the housing 400 of the pulse oximetry device 100. The exampleof the housing 400 as shown in FIG. 6 differs from the example of thehousing 400 as shown in FIG. 4 by a cover structure 450 arranged on theupper side 401 of the housing 400 and fully covering the upper side 401of the housing 400, including the openings of the cavities 410, 420,430. The cover structure 450 comprises an optically transparentmaterial, for example, an optically transparent film. The coverstructure 450 may, for example, be formed by a KAPTON film. The coverstructure 450 may be used to protect the light emission devices 200 andthe light detection device 300 of the pulse oximetry device 100 fromdamage by external influences. Furthermore, the cover structure 450 maycause a further reduction of undesired crosstalk between the lightemission devices 200 and the light detection device 300.

Our devices and methods have been illustrated and described in detailwith the aid of the preferred examples. This disclosure is not, however,restricted to the examples disclosed. Rather, other variants may bederived therefrom by those skilled in the art without departing from theprotective scope of the appended claims.

This application claims priority of DE 10 2014 117 879.3, the subjectmatter of which is incorporated herein by reference.

1.-18. (canceled)
 19. A pulse oximetry device comprising: a lightemission device configured to emit light with a wavelength in a firstwavelength interval and light with a wavelength in a second wavelengthinterval, a first light detector configured to detect light with awavelength in the first wavelength interval, but not to respond to lightwith a wavelength in the second wavelength interval, and a second lightdetector configured to detect light with a wavelength in the firstwavelength interval and detect light with a wavelength in the secondwavelength interval, wherein the first light detector has a first lightreception surface, the second light detector has a second lightreception surface, and the first light reception surface and the secondlight reception surface are arranged in a common plane and areinterleaved with one another.
 20. The pulse oximetry device according toclaim 19, wherein the first wavelength interval and the secondwavelength interval do not overlap one another.
 21. The pulse oximetrydevice according to claim 20, wherein the first wavelength interval orthe second wavelength interval lies below a wavelength of 810 nm, andthe other wavelength interval lies above a wavelength of 810 nm.
 22. Thepulse oximetry device according to claim 19, wherein the first lightdetector has a filter configured to filter out light with a wavelengthin the second wavelength interval.
 23. The pulse oximetry deviceaccording to claim 19, wherein the light emission device is configuredto emit light with a wavelength in the second wavelength interval with ahigher power than light with a wavelength in the first wavelengthinterval.
 24. The pulse oximetry device according to claim 19, whereinthe light emission device has a first light-emitting diode structureconfigured to emit light with a wavelength in the first wavelengthinterval, and a second light-emitting diode structure configured to emitlight with a wavelength in the second wavelength interval.
 25. The pulseoximetry device according to claim 24, wherein the first light-emittingdiode structure and the second light-emitting diode structure arearranged in a common light-emitting diode chip.
 26. The pulse oximetrydevice according to claim 25, wherein the first light-emitting diodestructure and the second light-emitting diode structure are arranged orstacked on top of one another.
 27. The pulse oximetry device accordingto claim 24, wherein the light emission device has a firstlight-emitting diode chip having the first light-emitting diodestructure, and a second light-emitting diode chip having the secondlight-emitting diode structure.
 28. The pulse oximetry device accordingto claim 19, wherein the pulse oximetry device has a housing with anemitter cavity and a detector cavity, the light emission device isarranged in the emitter cavity, and the first light detector is arrangedin the detector cavity.
 29. The pulse oximetry device according to claim28, wherein the second light detector is arranged in the detectorcavity.
 30. The pulse oximetry device according to claim 28, wherein theemitter cavity and the detector cavity are open to a common surface ofthe housing.
 31. The pulse oximetry device according to claim 28,wherein a wall of the emitter cavity forms an optical reflector.
 32. Thepulse oximetry device according to claim 28, wherein the housing has afurther emitter cavity in which a further light emission device isarranged.
 33. A method of operating a pulse oximetry device comprising:emitting light with a wavelength in a first wavelength interval andsimultaneously emitting light with a wavelength in a second wavelengthinterval; recording a first measurement signal with a first lightdetector configured to detect light with a wavelength in the firstwavelength interval, but not to respond to light with a wavelength inthe second wavelength interval; recording a second measurement signalwith a second light detector configured to detect light with awavelength in the first wavelength interval and detect light with awavelength in the second wavelength interval, wherein the first lightdetector has a first light reception surface, the second light detectorhas a second light reception surface, and the first light receptionsurface and the second light reception surface are arranged in a commonplane and are interleaved with one another; and calculating an oxygensaturation from the first measurement signal and the second measurementsignal.
 34. The method according to claim 33, wherein a differencesignal is formed from the difference of the first measurement signal andthe second measurement signal, and the oxygen saturation is calculatedfrom the first measurement signal and the difference signal.
 35. Themethod according to claim 33, wherein the light with a wavelength in thesecond wavelength interval is emitted with a higher power than the lightwith a wavelength in the first wavelength interval.